Chemical process



Sept. 10, 1946. c. s. LYNCH ETAL 2,407,311

CHEMICAL PROCESS Filed March 6, 1943 v CATA I VST .DRA W of?? lo Rem/egg Pra/VP.

Patented'sept. 10, 1946 CHEMICAL PROCESS Charles S. Lynch, Plainfield, and Howard G.

Codet, Mountainsde, N. J assignors to Standard Oil Development Company, a corporation of Delaware Application March 6, 1943, Serial No. 478,184

The present invention relates to improvements in the art of. producing aviation gasoline and, more particularly, it relates to a method of producing 2,3 dimethyibutane by aikylanng emmene f with isobutane. In the application of Ralph M. Hill and Charles l-I. Watkins, Serial No. 472,192, filed January 13, 1943, there is described a method of alkylating ethylene with a catalyst comprising an aluminum chloride-hydrocarbon complex to yield 2,3 dimethylbutane, a substance which when used as a fuel in an internal combustion 9 Claims. (Cl. .E60-683.4)4

' ucts pass from the top-of the reactor.

Referring to the drawing, I is a reactor, Carrying a pressure gauge 20, preferably consisting of a cylindrical shell or case, packed With a suitable packing material such as Raschig rings R, and 5 is a settling zone into which reaction prod- In the .settler 5, entrained catalyst material, i. e. the

engine, has a rich mixture performance rating such that, when it is'leaded with 4 cc. of lead tetraethyl per gallon, itis superior to pure iso octane plus 6 cc. of leadtetraethyl per gallon. In theaforesaid application, all of the aluminum chloride was addedr at the begnning of thereaction and after an induction period, the catalyst vcomprising the said aluminum' chloride-hydrocarbon complex was formed whereupon the' We have now discovered a method forirnproving the operation described in the saidapplication of Ralph M. Hill and Charles Watkins, and in its essence our invention involves'supplying fresh aluminum chloride to the' circulating stream of reactants and recycled product inincrernental portions rather ythan adding the total quantity at thebeginning. By thus proceeding,

we greatly reduce the' induction vperiod requiredl to form the'catalytically active aluminum ehlof.

It is pointed out ride-hydrocarbon complex. that as in the process described in the aforesaid application of I-Iill et al.,'the catalyst isv formed' by the interaction between isoparaflinic, olenic hydrocarbons and AlCls.v

An object of our inventiontherefore is to alkylate mono-olens7 particularly ethylene or propy1- AlCl; hydrocarbon complex collects at the bottom and may be withdrawn thro-ugh line 2I. Of

course, other portions of the AlCls complex which venter 5 may gravitate back into I. But 2| provides a method of withdrawing spent catalyst from the system. However, during the early phases of the operation all of the AlCls which enters Zone 5 gravitates or drains back into reaction zone I and itis only after the process is oil-stream fora relatively long period .of time 100 hours ormore) that Spent catalyst is Withdrawn through line' 2 I, in the ordinaryfmethod of operating; However, v.if the tower should become lled with catalyst and then flowed into Zone 5 (thuseontaminating the productstream I5) before the time period stated, obviously the valve in line 2I'shou1dbe opened to draw oiT catalyst.

, actor I.

V'ducted throughline I5 to distillation, washing ene, with isoparaiiins such as isobutane, and the` like in the presence of ya catalytically active aluminum chloride-hydrocarbon complex under conditions such that the induction period necessary for the formation of a catalytically active; raluminum chloride-hydrocarbon complex, whichv promotes the formation of an alkylateof desired high quality, isgreatly reduced.

Another object of ourinventionis to ,scoper- Vflow plan illustratingapreferred modi-flcationvof our invention..

ate the .alkylationfof ethylene with isobutane as -to enable the process to functonf'continuously.

The product is withdrawn through line I0 and a portion of this material containing in addition to the desired 2,3 dimethylbutane, unreacted isobutane is recycled Via line II and pump' I2 to re- The remainder of the product is conand purificationvequipment adapted to yield a pure product; The isobutane yremoved from the product during finishingis recycled to the reactor Ithru the hydrocarbonfeedline 2 for further use inv the process. The method of zpurifying the Lproduct is omitted for purposes of simplicity of `explanation and because the invention resides in other features of our process.

The recycled material in line I I may be passed via pipe II through fresh AlCla container I8 and thence through rpipes I9 and `22 into .the reactor. Meanwhile,` fresh feed containing ethylenev and isobutaneis dischargedintorhe reactor I through pipe 2. The ratio of isobutane to ethylene -in the fresh feedmay be'relatively low, say .4 mols of isobutane tov 3 of ethylene. ing a high'recycle ratio, say from l0 to'lGD v01.- -umes of liquid inr recycle line II to one volume of 'liquid feed in line v, a high internal ratiol of isobutane to olefin is maintained in reactor I. This internal ratio Aof isoparaflin to oleiinmayarnount :fromj 10 to 100 or more mols of isoparaiiinper mol of olefin.

'We consider the crux of our invention to reside in the manner of operating the process with respect to the addition of AlCla from a reservoir I8.l

We 'start :theoperation by first filling-,the reactor with `liquid isobutane, satura-ting the isobutane However, by employreactor I. During the iirst phase of the operations nearly all of the material recovered from the top of the reactor is recycled by way of pipes II, IT, reservoir IS and pipes I9 and 22 to the reactor I. In. passing thro-ugh the reservoir I8 fresh A1Cl3 is absorbed or acquired by the owing 2.5 lbs. AlCla charged Promoter: ethyl chlo 4 ber, namely an octane number of 94 as determined by the A. S. T. M. (American Society for Testing Materials) some time between the 5th and 8th hour so that from at least the 8th hour until the end of the operation the octane number of the Cs fraction was considerably above 90.

We set forth below the result of a second run which we made, including operating conditions and an inspection of the product. In this run, all of the AlCla was added at the start of the operation, and it will be noted that the product distribution as well as the yields were low due to excessive cracking, no doubt, as evidenced by the large amounts of low molecular Weight hydrocarbons. Also the octane number was low up to 21-24 hours.

Table II.-Ethylene alkylation tower at start. ride.

Pressure: 275 lbs. sq. in.

Temp.: 105-110 F. n

Feed: 27 mole C2H4/hr.; iso C4/C2=mol ratio 3/1 (in fresh feed).

Hours of operation 5-8 Net percent alk. on Cz- F. (C5) 40 31 34 24 14 11 8 5 11G-165 F. (Cs) 39 46 43 52 62 64 64 52 165-265o F. (C1-CSL--- 16 17 16 17 18 18 20 26 265 F.-|-(Cul) 5 6 7 7 6 7 8 17 ASTM o No.:

Ca 85. 7 85.6 89. 1 91. 9 92. 5 93.6 C11-Cs 69.8 85. 6 73.8

In other words, at the beginning of the operation 0.45 lb. of aluminum chloride was placed in receptacle I8 and the recycle stock passed through the receptacle containing the aluminum chloride. This was continued for a period of two hours, whereupon a second 0.45 lb. portion of aluminum chloride was added to receptacle I8. This procedure was repeated at the sixth and eighth hours until all of the 1.8 lbs. of aluminum chloride was added. No more aluminum chloride was added after that until at the 54th hour whereupon another 0.22 lb. of aluminum chloride was added to receptacle IS. The addition of aluminum chloride continued at the 66th, '78th,90th, 102nd, and 114th hours until a total of 3.1 lbs. of aluminum chloride had been added. A temperature of 105 F. and a pressure of 275 lbs. per square inch gauge was maintained within the reactor.

- As a result of the ope-ration, we set forth below thedata obtained as a result of the continuous run:

We wish to point out that best results are obtained by maintaining a high recycle ratio. That is to say from 10 to 100 volumes of the product is recycled via line I0 and pump I2 to the reactor per volume of fresh feed (ethylene plus isobutane), in line 2. The purpose of this high recycle ratio is to maintain a high ratio of isoparaiiin to olen in the reactor for it has been foundthat this high ratio improves both the quality of the product and the yield.

To recapitulate, our present invention relates to a continuous method of alkylating ethylene with isobutane to form substantial quantities of 2,3 dimethybutane which is a very valuable blending agent in the manufacture of aviation fuels. We have found it advantageous to add the catalyst to the system in incremental portions rather than to add the catalyst at o-ne time for we reduce the number of hours necessary for the catalyst to attain maximum activity. In other words, where the catalyst is formed in situ by interaction Table I.-Ethylene'z'sobutane aZlcyZatz'onf--contnuous tower Catalyst: A1013 (l). Promoter: C1HOl(2)/.

Mol ratio: liso C4/C2=3.0 (in fresh feed). Pressure: 2751bs./sq. in.

Hours of operation.. 5-8 9-12 17-20 29-32 105 106 104 100 C2H4mols/hr,. 10 10 7.5 7.5 Wt. per cent (J5-talk. on 02H4 fed (cumulativ 187 208 222 Wt. per cent CVI-slk. on 02H4 fed c011- sumed (cumulative) 197 220 242 262 Yield gal. alk. (cumulative) 1 54 4.12 6. 76 Yield gal. alk/lb. A1013 (cum 2. 3 3. 8 Vol. per cent alk.:

ASTM oct. No ss. 2

It isobvious from the above data that the fraction of the product which is the most important fraction, namely the C6 fraction or that fraction boiling from 11G-165 F., had a high octaneV num- 1 Iso C4=isobutane 75 which the alkylate` formed, particularly the Cs fraction, is of inferior quality particularly as regards octane rating. We have found that we may reduce the induction period very substantially by adding the catalyst in incremental portions rather than by adding to the system all of the catalyst intended to be used in one total quantity.

In order to operate our process continuously, it is obvious that two or more receptacles I8 should be provided and these may be operated in parallel so that the hydrocarbon recycle in line I I may be alternately fed through the receptacles, that is to say, while one of the receptacles I8 is being recharged with catalyst, the other may be on the onstream operation thus maintaining co-ntinuity of operation.

As to operating conditions in the reaction zone the temperature may vary froml 90 to 175 F. with 100 to 110 F. preferred, the pressure may vary from 100 to 1000 lbs. per square inch gauge with 200 to 400 lbs. preferred, and we use from 0.04 lb. to 0.08 lb. of AlCla per gallon of alkylate produced in the system.

By an analogous method we may alkylate ethylene, propylene, butylene and other mono-olens with isobutane or some other isoparanin such as isopentane.

Many modifications of our invention will readily suggest themselves to those who are familiar with this art.

What we claim is:

1. In the process of continuously alkylating ethylene with an isoparafiin, the improvement which comprises forcing a mixture containing isoparain and ethylene through a catalyst charg-V ing zone containing aluminum'chloride and which can be recharged therewith from time to time whereupon a portion of said aluminum chloride is absorbed in the said mixture, forcing the mixture containing the aluminum chloride into a reaction zone, permitting the ethylene, isoparaiiin and aluminum chloride to remainrin contact with each other for a suicient period of time to form a catalytically active aluminum Vchloride-hydrocarbon complex, thereafter continuing 'the flow of isoparaii'in and ethylene through the catalyst charging zone and through the reaction Zone, maintaining the reaction zone at elevated temperatures and pressures during the process and A vwithdrawing from the reaction zone a product 3. 'Ihe method set forth in claim 1 in which a ratio of at least 100 mols of isoparafn per mol of olefin is maintained in the reaction zone.

4. A continuous method for alkylating ethylene with isobutane which comprises mixing ethylene with isobutane in a reaction zone containing an inert contact material, withdrawing a mixture of unreacted ethylene and isobutane from said reaction zone, recycling the mixture through a catalyst charging zone containing AlCls and thence to a reaction zone, maintaining the circulatory system indicated during the early phases of the process for an induction period suiciently long to permit the formation of AlCla hydrocarbon complex by interreaction of said AlCla and said hydrocarbons, simultaneously feeding isobutane and ethylene to said reaction, during said induction period, withdrawing a portion of the stream leaving the reaction zone as product folin the reaction zone.

8. The method specied in claim 4 in which the reaction is carried out at temperatures within the isobutane, the improve-ment which comprises pro- Viding `a body of AlCls in a catalyst charging zone, feeding isobutane and ethylene to a reaction Zone, withdrawing a recycle stream containing unreacted ethyleneand isobutanefrom said reaction zone, flowing said recycle stream through said body of AlClaA in the catalyst charging zone to said reaction zone for a period of 5 to 8 hours until the reaction product shows an octane number above 90, then withdrawing the reaction product, and adding A1013 in aliquot proportions from time to time by directing the recycle stream through the catalyst charging Zone and thereby maintaining the octane numbervof the product continuously above 90.

CHARLES S. LYNCH. HOWARD G. GODET. 

